Conventionally, there are known various types of ceiling fans suspended from a ceiling for use. For example, the conventional ceiling fan includes a coupling portion having an upper part supported on a ceiling, a rotary driving portion attached to a lower part of the coupling portion, a plurality of blades to be rotated by the rotary driving portion, and a support portion to which root portions of the blades are attached in a mounting state. The rotary driving portion has a stator fixed to the coupling portion and a rotor to be rotary driven around the stator. The support portion is fixed to the rotor. When the rotor is rotary driven, the respective blades attached to the support portion are rotated together with the support portion.
The conventional ceiling fan having the structure is devised in respect of safety, for example, a blade fall preventing portion is provided so as not to separate the blades from the support portion even if the blade is broken in the root portion (see Patent Document 1, for example).
A structure of the blade fall preventing portion provided in the conventional ceiling fan will be described with reference to FIG. 15 showing an attachment state to a support portion 112 in a root portion 111 of a blade 110. As shown in FIG. 15, the root portion 111 of the blade 110 has a screw fastening holes 113 (two places) provided in the vicinity of both ends in a width direction and an engaging hole 114 (one place) provided on a center in the width direction. Moreover, an engaging portion 115 protruded from an upper surface is provided on the support portion 112.
As shown in FIG. 15, the root portion 111 of the blade 110 is fastened with a screw by using the fastening holes 113 in the two places in a mounting state on the upper surface of the support portion 112. Consequently, the blade 110 is brought into an attachment state to the support portion 112. In the attachment state, furthermore, the engaging portion 115 of the support portion 112 penetrates the engaging hole 114 of the root portion 111 on the blade 110.
In the case in which a vicinal part of the fastening hole 113 is broken in the root portion 111 of the blade 110, for example, the engaging portion 115 is engaged with the engaging hole 114 so that the blade 110 can be prevented from falling. Referring to the conventional ceiling fan in FIG. 15, thus, the blade fall preventing portion is configured from the engaging portion 115 and the engaging hole 114.